The invention relates to a driver assistance system for a road vehicle, and a method for operating such a driver assistance system, whereby the driver assistance system captures environment information about a vehicle's environment; and a moving direction and/or a speed of the vehicle are influenced as a function of the environment information.
Such driver assistance systems are already known. Depending on the particular implementation, they fulfill various tasks, which otherwise are the sole responsibility of the driver. In one realization, pictures of the roadway in front of the driving car are taken by a camera and evaluated. Especially by means of roadway markings, which are in the middle, or at the edge of the roadway, information can be captured this way with respect to whether the vehicle is at a sufficient distance from the edge, the middle, and/or a lane delimitation of the roadway. The driver assistance system may then influence the traveling direction, if needed, for example, to make sure that the vehicle does not inadvertently leave a lane.
A further realization of a driver assistance system of the above-mentioned type is described in German patent document DE 198 04 641 A1: Depending on the distance to a vehicle driving ahead, the system influences the driving speed of the vehicle.
Driver assistance systems of the type mentioned at the beginning ease the strain on the driver, on the one hand by at least partially taking over the task of taking measures for conducting the vehicle by using information about the vehicle's environment. On the other hand, there are driving situations in which the driver assistance system may not be operated, or operated reliably, because the limits of an operating range, for which the driver assistance system was designed, are reached, or exceeded. If the driver does not observe the appropriate system limits and still relies on the system in these driving situations, traffic conflicts may be caused.
The present invention is based on providing a method and a driver assistance system of the above-mentioned type which allow for conflict-free application of the driver assistance system.
To meet these needs, the present invention outputs help information to the driver during the operation of the vehicle with respect to the driver assistance system in order to detect whether the driver assistance system may be reliably operated in an instantaneous, and/or in a future expected condition of the vehicle environment and/or operating condition.
“Operating reliably” as described above means that the driver assistance system is operated within an operating range for which it is designed. The corresponding system limits of the operating range, or the operating ranges may be at hand for various reasons. A sensor of the system may, for example, provide no or merely imprecise measuring signals within, or outside of a certain value range of the to be captured observation factor. Also, a further processing of the signals in certain operating situations of the vehicle (e.g. while the vehicle moves in dense traffic) may not be possible, or only in a restricted way, or may lead to unusable results for the driver assistance system. Furthermore, there are physical limits (e.g. temperature range) for the application of the system, and limits, or voids in the evaluability of an actual operating situation of the vehicle by the system. For example, the driver assistance system (see above) described in German patent document DE 198 04 641 A1 may not react to parked or standing vehicles, because there normally are a number of other non-moving objects apart from the parked or standing vehicles.
It is furthermore provided, that the driver assistance system consists of a help system for the output of help information to the driver of the vehicle, and that the driver assistance system consists of detection instruments for detecting whether the driver assistance system may be reliably operated in an instantaneous, and/or in a future expected condition of the environment and/or operating condition of the vehicle. The help system is connected with the detection instruments, and is designed to notify the driver during the operation of the vehicle when the driver assistance system cannot be operated reliably.
The present invention is based on the idea that it is becoming more and more difficult for drivers to learn the utilization and/or operation of the increasingly more complex driver assistance systems. Written operating instructions therefore become more and more extensive and complicated. It is also a know fact, that only few users read all the operating instructions, and/or remember all the important details during the utilization or operation. The safety is therefore enhanced, if help information regarding the correct usage and/or operation, especially about system limits during the operation of the vehicle are being output to the driver, and preferably at a time when an operating situation of the driver assistance system assigned to the relevant help information is imminent and/or has occurred.
A driver assistance system is, for example, designed to maintain a sufficient distance to the vehicle driving in front. The driver assistance system, however, only reacts to moving objects, and therefore cannot reliably keep a distance to standing, or very slow moving vehicles, i.e. it cannot stop the vehicle in time. If the speed of a vehicle driving in front falls to, or below, a preset limit value, a warning is output to the driver for this reason.
Preferably, the help information is at least partially output as acoustic and/or haptic signals, so that the attention of the driver to visual impressions of the environment of the vehicle is not impaired. A warning signal may, for example, be output to the driver in that at least a section of the steering wheel and/or the driver's seat outputs a haptic signal, e.g. in the form of a repeatedly interrupted vibration. Optionally, and/or in addition, an explanation of the situation may occur per voice output.
It is furthermore preferred to detect which driver is driving the vehicle, and to determine as a function thereof, whether and/or which help information is being output to the driver. Thereby, for example a differentiation can be made between an experienced user of the driver assistance system and a new user. Whereas the new user is still alerted to numerous operating situations of the driver assistance system, to the experienced driver at the most only minimal help information is provided. Thus, it can be prevented, that an advanced or experienced user is supplied with unnecessary information, and therefore pays no, or only little, attention to the help information that is output.
A possibility for differentiating users according to their different experience is to increase the value of a counter by one, each time a certain driver turns the driver assistance system on or off. It is, however, preferable, to record a history of help information already given to the driver, and to decide based on this history, whether and/or which help information is being given to the driver. As an alternative, or in addition, one or both of the following measures for determining the level of experience of a certain driver can be performed: a reaction of the driver to already output help information is evaluated, or a utilization of the driver assistance system and/or at least one other device of the vehicle by the driver is evaluated. Furthermore, for example, operating errors of the driver may be captured, and as a function thereof it may be decided whether and/or which help information should be output to the driver.
It seems expedient to output certain help information to the driver only a predetermined number of times, for example, two or three times. Thereafter, it can be assumed, that the driver does not need this information any longer. In a modification, in addition, or as an alternative, it may be taken into consideration how long it has been since certain help information was last given to the driver. If the last output goes back more than a predetermined period of time, the help information is given to this driver independent of, whether it was output previously on one or more occasions. It is also possible to make the output of certain help information a function of the period of time since the last output, and the number of past outputs.
By using biometric methods and/or by means of an object unmistakably allocated to a person it may, for example, be determined which driver is driving the vehicle.